K. D. Ianakiev

• Los Alamos National Laboratory

Detecting shielded special nuclear material, such as nuclear explosives, is a difficult challenge pursued by non-proliferation, anti-terrorism, and nuclear security programs worldwide. Interrogation with intense fast-neutron pulses is a promising method to characterize concealed nuclear material rapidly but is limited by suitable source availabilit...

Compact, bright neutron sources are opening up several emerging applications including detection of nuclear materials for national security applications. At Los Alamos National Laboratory, we have used a short-pulse laser to accelerate deuterons in the relativistic transparency regime. These deuterons impinge on a beryllium converter to generate ne...

Composite materials have the potential to play an important role in enabling high-performance and cost-effective neutron detectors for fundamental science, global security, and dosimetry applications. This study presents neutron and gamma transport simulation results on composites consisting of ⁶Li-containing GS20 scintillator glass particles arran...

Composite materials consisting of ⁶Li scintillator particles in an organic matrix can enable thermal neutron detectors with excellent rejection of gamma-ray backgrounds. The efficiency of transporting scintillation light through such a composite is critical to the detector performance. This optical raytracing study of a composite thermal neutron de...

To enhance the capabilities of the DANCE array, a new detector array NEUANCE was developed to enable simultaneous measurements of prompt fission neutrons and γ rays. NEUANCE was designed and constructed using 21 stilbene organic scintillator crystals. It was installed in the central cavity of the DANCE array. Signals from the 160 BaF2 detectors of...

Improving the quality of safeguards measurements at Gas Centrifuge Enrichment Plants while reducing the inspection effort is an important objective given the number of existing and new plants that need to be safeguarded. A useful tool in many safeguards approaches is the on-line monitoring of enrichment in process pipes. One requirement of such a m...

Laser-plasma interactions in the novel regime of relativistically induced transparency (RIT) have been harnessed to generate intense ion beams efficiently with average energies exceeding 10 MeV/nucleon (>100 MeV for protons) at “table-top” scales in experiments at the LANL Trident Laser. By further optimization of the laser and target, the RIT regi...

A short-pulse laser-driven deuteron beam is generated in the relativistic transparency regime and aimed at a beryllium converter to generate neutrons at the TRIDENT laser facility. These prompt neutrons have been used for active interrogation to detect nuclear materials, the first such demonstration of a laser-driven neutron source. During the expe...

A fission-fragment detector based on thin scintillating films has been built to serve as a trigger/veto detector in neutron-induced fission measurements at DANCE. The fissile material is surrounded by scintillating films providing 4π detection of the fission fragments. The scintillation photons were registered with silicon photomultipliers. A measu...

International safeguards inspectorates (e.g., International Atomic Energy Agency {IAEA}, or Euratom) rely heavily on neutron assay techniques, and in particular, on coincidence counters for the verification of declared nuclear materials under safeguards and for monitoring purposes. While ³He was readily available, the reliability, safety, ease of u...

Investigation of prompt fission and neutron-capture Υ rays from fissile actinide samples at the Detector for Advanced Neutron Capture Experiments (DANCE) requires use of a fission-fragment detector to provide a trigger or a veto signal. A fission-fragment detector based on thin scintillating films and silicon photomultipliers has been built to serv...

Most 3He replacement neutron detector technologies today have overlapping neutron-gamma pulse-height distributions, which limits their usefulness and performance. Different techniques are used to mitigate this shortcoming, including Pulse Shape Discrimination (PSD) or threshold settings that suppress all gammas as well as much of the neutrons. As a...

In this paper, we report our progress toward the development of an advanced enrichment monitoring technology for safeguarding gas centrifuge enrichment plants. We compare the UF6 gas pipe attenuation and sensitivity to X-ray tube HV variations for two transmission energies: 22 keV and 25.5 keV. The first experimental enrichment results taken with a...

The Swedish Nuclear Fuel and Waste Management Company (SKB), European Atomic Energy Community (Euratom), two universities and several U.S. Department of Energy Laboratories have joined in a collaborative research effort to determine the capability of non-destructive assay (NDA) techniques for spent fuel to meet the combined needs of the safeguards...

The new plastic scintillators with n/γ pulse shape discrimination (PSD) properties being developed by the Lawrence Livermore National Laboratory (LLNL) and commercialized by Eljen Technology are addressing the toxicity and flammability issues of liquid scintillators, thus enabling a much wider range of practical applications for the detection of ne...

Transmission measurements of radiation through process pipes provide a non-intrusive method of determining the amount of product present in the pipes. The product could be a liquid, a slurry, or a gas, which is the most challenging because of the low density. Traditionally, these techniques have used a radioactive source that has to be replaced per...

We present a method of determining the wall thickness of a pipe in a Gas Centrifuge Enrichment Plant (GCEP) when an empty pipe measurement is not feasible. Our method uses an X-ray tube for transmission measurements and a lanthanum bromide (LaBr3) scintillation detector on the opposite side of the pipe. Two filters, molybdenum (K-edge 20.0 keV) and...

Increasing needs for neutron detection and limited supply of 3He have led to the need for replacement neutron detection technology. This paper presents the design and initial results for a neutron detector (6Li foil scintillator sandwich) that uses lithium metal foil to detect thermal neutrons. The reaction products, primarily triton, deposit most...

A flux monitor diode is being explored as an option for measurement of the output of an X-ray tube that is used for active transmission measurements on a pipe containing UF6 gas. The measured flux can be used to correct for any instabilities in the X-ray tube or the high voltage power supply. For this measurement, we are using a silicon junction p-...

We previously reported on calculations for a proposed method of determining the thickness of a pipe in a gas centrifuge enrichment plant (GCEP) when an empty pipe measurement is not feasible. 1 This method uses an X-ray tube for transmission measurements and a LaBr3 scintillation detector on the opposite side of the pipe. Two filters, molybdenum (M...

Current safeguards approaches used by the International Atomic Energy Agency (IAEA) at gas centrifuge enrichment plants (GCEPs) need enhancement in order to verify declared low-enriched uranium (LEU) production, detect undeclared LEU production and detect highly enriched uranium (HEU) production with adequate detection probability using non destruc...

Current safeguards approaches used by the International Atomic Energy Agency (IAEA) at gas centrifuge enrichment plants (GCEPs) need enhancement in order to verify declared low-enriched (LEU) production, detect undeclared LEU production and detect highly enriched uranium (HEU) production with adequate detection probability using nondestructive assa...

We report our developments of the next generation of uranium enrichment monitoring technology for gas centrifuge enrichment plants (GCEPs). The main challenge presented by current technology is the need for periodic replacement of the short half-life (1.27 year) 109Cd transmission source. We report on a transmission source at the 22.1 keV K-edge of...

In support of the development of an x-ray tube based source for transmission measurements of UF6 gas, we have developed a one-dimensional, spreadsheet-based model of the source. Starting with the spectrum produced by an x-ray tube we apply the linear attenuation coefficients for various notch filters, the aluminum pipe, and UF6 gas. This model allo...

In this paper we report our progress toward the development of an advanced enrichment monitoring technology for safeguarding gas centrifuge enrichment plants. We compare the UF₆ gas pipe attenuation and sensitivity to X-ray tube HV variations for two transmission energies: 22 keV and 25.5 keV. The first experimental enrichment results ta...

We report our progress toward development of new generation on-line enrichment monitoring technology for UF 6 gas centrifuge plants based on a transmission source and a NaI spectrometer. We use an X-ray tube with transmission filters instead of a decaying isotopic transmission source to eliminate the costly replacement of this source. The UF 6 gas...

Single neutron and gamma charge pulses were captured using a fast ADC. These data were used to populate simulated 5-µs active interrogation flash events. Analysis of these simulations revealed that long pulse tail accumulation during the flash leads to an unpredictable charge background for several microseconds after the flash. The existence of thi...

We measure the time dependence of the scintillator light-emission pulses in NaI(Tl) crystals at different temperatures, after activation by gamma rays. We confirm that there are two main nonexponential components to the time decay and find that their amplitude ratio shows Arrhenius temperature dependence. We explain these nonexponential components...

The time dependence of NaI(Tl) fluorescence was measured long time ago with the delayed coincidences method and two decay time components were observed. Because 95% of the total light yield is collected within the first 800 ns, the influence of the second component has been neglected. We claim that there are two dominant nonexponential light compon...

Techniques have been developed to exploit abundant prompt emissions from photonuclear reactions for the identification of special nuclear material (SNM). These enhancements are designed to reduce inspections times and delivered dose in systems which have, historically, relied solely on delayed emissions. Experimental evidence is presented for promp...

This paper is a continuation of our work that describes the temperature behavior of doped NaI(T1) scintillators as a convolution between the temperature-dependent shape of the light output and the pulse-response function of the shaper. The effects from temperature and shaping on the nonproportionality of the NaI(T1) gamma spectrum are evaluated. We...

NE-213 liquid scintillation detectors are currently used in radiation fields consisting of both gamma rays and fast neutrons and are an excellent tool for differentiating between each type of radiation via their respective interactions. In this experiment, an analysis was performed on an NE-213 liquid scintillation detector to investigate the effec...

Active interrogation with pulsed bremsstrahlung beams can saturate detectors and produce high count rates of overlapping pulses in the prompt region (<1 mus) after the interrogating pulse. We describe a method to eliminate saturation by modifying the photomultiplier voltage divider and by gating intermediate pairs of dynodes and the anode. To proce...

A technique for eliminating the long component for gamma pulse response in liquid scintillators has been developed. The analytical relationships between the values of the electrical components and the light response, approximated with two and three exponential components, have been derived. A simple reset preamplifier was built for acquiring and di...

We have studied the stability of a NaI(T1) scintillation detector and a commercial, general-purpose, digital, multichannel analyzer (MCA) used in uranium enrichment monitoring and have evaluated their combined sensitivity to temperature. The method used to calculate enrichment is very sensitive to any error that may be introduced by the instrument...

It is a familiar fact that the total measured light yield of NaI (Tl) detectors is a nonlinear function of temperature. Here we present new experimental data for the temperature behavior of doped NaI(Tl) scintillators that instead shows a linear dependence of light output over a wide temperature range- including that for outdoor applications. The s...

It is a familiar fact that the total measured light yield of NaI (Tl) detectors is a nonlinear function of temperature. Here we present new experimental data for the temperature behavior of doped NaI(Tl) scintillators that instead shows a linear dependence of light output over a wide temperature range- including that for outdoor applications. The s...

When a novel neutron-capture lithium pulse-mode ionization chamber (LiPMIC) was designed to replace He proportional counters as a more economical solution for some homeland security and counter-terrorism applications for large-scale, long-term remote sensors, this brought on a fundamental disadvantage of possibly exposing the ionization chamber to...

The temperature dependence of inorganic scintillators is nonlinear over the temperature range for outdoor implementation, mainly due to the complex change of the light yield as well as light decay time over the temperature range. Our spectrum stabilization approach is based on rough and prompt control of effects of the temperature drift that keeps...

We describe the development of a large area neutron detector based on a pulse-mode ionization chamber lined with ⁶Li foil in a low-cost housing of HDPE (high density polyethylene) that serves as the moderator. The use of inexpensive materials, technology for mass production and simple construction, which integrates the basic components o...

A new neutron multiplicity counter is being developed which utilizes the fast response of liquid scintillator (NE-213) detectors. Current uranium coincidence counting methods rely on the assay samples to conform to the calibration standards with respect to the sample uniformity, geometry, material type, etc. There exists a wide range of material th...

There has been a long-standing need for a room-temperature gamma-ray detector system with high efficiency and adequate resolution for nuclear safeguards applications. For nuclear safeguards, measurements must resolve the uranium complex at 186keV and the plutonium complex at 414keV. The need for adequate room-temperature resolution has been met by...

A unique detector design incorporating a Li-based capture medium, ZnS scintillator, and wavelength shifting optical fibers is the basis of a new neutron coincidence counter for measurements of plutonium in highly-impure residues. The sensor elements have a high efficiency for detecting neutrons and exhibit excellent gamma-ray discrimination based o...

Segmented and pixilated electrode structures are used to compensate for poor hole transport in CdZnTe devices used for gamma-ray spectrometry and imaging. Efforts to model these structures have focused primarily on geometric effects; however, device performance also depends on the physical properties of the bulk and surface material, as well as the...

A new well counter has been developed at Los Alamos National Laboratory that integrates the neutron capture medium (6LiF) and scintillator (ZnS) into a thin screen, which is coupled to wavelength shifting fiber-optic ribbon. A foursided prototype well counter has been built. It has a short neutron die-away time (t = 5.8 {micro}s), which increases i...

We present results of experiments to characterize two large- volume, multi-element CdZnTe detectors for gamma-ray spectroscopy at high energy. The first detector consisted of four 1.5cm x 1.5cm x 0.75cm coplanar grid detectors. The measurements for the four-element design were performed with various configurations. The second detector consisted of...

A fast neutron coincidence counter using BC454/BGO phoswich detectors has been evaluated for the purpose of rapid verification measurements of uranium items. This counter uses custom electronics to identify and count coincidence neutrons in the presence of background radiation. Measurements of uranium standards were performed to evaluate the counte...

We describe the development of detector arrays and electronics for large-volume, hand-held CdZnTe detectors with the same counting efficiency as portable NaI(Tl) detectors presently used for nuclear material measurement applications. The pulse-height resolution of the multi-element detectors is at least three times better than NaI(Tl) over a wide e...

Many applications using gamma rays, such as the determination of the elemental composition of planetary bodies, require the detection of gamma rays in the energy range 100keV-10MeV in a light, compact, room-temperature system. The photopeak efficiency of a single CdZnTe detector is limited because the volume currently available is limited to about...

We present high energy results for a 2 x 2 x 2 array of eight 10 mm x 10 mm x 5 mm coplanar grid CdZnTe detectors. We conclude that such an array can provide a room-temperature detector with good resolution and efficiency for planetary missions. Additional information is contained in the original extended abstract.

In this paper, we present results of experiments to characterize a large-volume (4 cm 3 ), multi-element CdZnTe detector for high-efficiency, gamma-ray spectroscopy. The module includes an array of eight 0.5 cm 3 coplanar grid detectors manufactured by eV Products. An eight-channel data acquisition system with list mode output is used to record gam...

Quantities of special nuclear material (SNM) are measured by counting coincident neutrons. This technique relies on spontaneous fission, in which more than one neutron is released for most events. Neutron coincidence counting (NCC) uses thermal neutron detectors. A problem with measurements of impure materials is that the neutron count rate, which...

Recent results from encapsulated multi-element CdZnTe room-temperature semiconductor gamma-ray detectors are presented. Our multi-element-array design is a good low-mass and low-power candidate for elemental mapping on future planetary missions.

Single-element CdZnTe detectors are limited in size, and therefore efficiency, by the poor hole transport, even with a coplanar grid. We are investigating the possibility of a 27-element (3 × 3 × 3) array using 15 mm × 15 mm × 15 mm elements for gamma-ray energies to 10 MeV for NASA planetary missions. We present experimental results for combinatio...

A prototype Compton camera using ambient-temperature semiconductor detectors is developed for gamma ray spectroscopic imaging. Two camera configurations are evaluated, one using an intrinsic silicon detector for the front plane detector and the other using a CdZnTe detector for the front plane. Both configurations use a large-volume coplanar grid C...

Results from large-volume CdZnTe semiconductor detectors for ambient-temperature gamma-ray spectroscopy are presented. Our new multi-element-array design is a good low-mass and low-power candidate for elemental mapping on future planetary missions.

CdZnTe is an attractive alternative to scintillator-based technology for ambient-temperature, gamma-ray spectroscopy. Large, single-element devices up to 3500 mm³ have been developed for gamma-ray spectroscopy and are now available commercially. Because CdZnTe is a wide band-gap semiconductor, it can operate over a wide range of ambient temperatur...

The authors have evaluated and compared some of the relevant operating characteristics of NaI and plastic scintillators for use in various safeguards monitoring applications. These include a sensitivity analysis of the two scintillators to various radiation fields and scintillator response as affected by environmental temperature. A comparison of e...

We are developing a set of tools to be used by the Safeguards Assay Group to solve problems found in safeguards and the domestic nuclear industry. The tools are also applicable to problems dealing with the environment, defense, and other areas of national and international interest. We have used extensively the advances in hardware and software sin...

Current safeguards approaches used by the IAEA at gas centrifuge enrichment plants (GCEPs) need enhancement in order to verify declared low enriched uranium (LEU) production, detect undeclared LEU production and detect high enriched uranium (HEU) production with adequate probability using non destructive assay (NDA) techniques. At present inspector...

In this paper we report on the design of a multilayer thermal neutron detector based on Li reactive foil and thin film plastic scintillators. The Li foils have about twice the intrinsic efficiency of ¹°B films and about four times higher light output due to a unique combination of high energy of reaction particles, low self absorption, and low ioni...

The outline of this presentation is: (1) Technology basis of on-line enrichment monitoring; (2) Timescale of trial; (3) Description of installed equipment; (4) Photographs; (5) Results; (6) Possible further development; and (7) Conclusions. Summary of the good things about the Advanced Enrichment Monitor (AEM) performance is: (1) High accuracy - no...

The authors report on the development of a subsystem that, when used with an Attribute Measurement System (AMS), can determine the current date without batteries, continuous electrical connection, or user input. The device will allow the system to determine the current date from the decay of a small radioactive source without complication of the in...

Prototypes of a Li-6 Pulse Mode Ionization Chamber (LiPMIC) have been in development for the past two years for the purpose of providing large-area neutron detector. this system would be suitable for remote deployment for homeland security and counterterrorism needs at borders, ports, and nuclear facilities. A prototype of LiPMIC is expected to pro...

The present invention includes an apparatus and corresponding method for temperature correction and count rate expansion of inorganic scintillation detectors. A temperature sensor is attached to an inorganic scintillation detector. The inorganic scintillation detector, due to interaction with incident radiation, creates light pulse signals. A photo...

We will discuss the testing and operation of a system that produces multiple sets of equivalent data from a single gamma detector. Verification or inspection operations often involve measurements made by outside agencies in facilities where space is constrained. Such measurements often involve expensive detectors. In a production facility, the time...

A thermal neutron detector has been developed that integrates the neutron capture medium (LiF) and scintillator (ZnS) into a thin screen, which is coupled to wavelength shifting fiber-optic ribbon. The LiF and ZnS powders are incorporated in a hydrogenous binder. The detector is constructed of alternating layers of the capture/scintillator screen a...

A new neutron coincidence counter with improved capabilities is being built as a commercial prototype. This counter uses LiF/ZnS(Ag) based scintillation detectors to achieve a short neutron die-away time ( < 5 s), which increases the sensitivity of the counter to measurements of ²°Pu by neutron coincidence counting. Greater sensitivity is required...

Improving the quality of safeguards measurements at Gas Centrifuge Enrichment Plants (GCEPs), whilst reducing the inspection effort, is an important objective given the number of existing and new plants that need to be safeguarded. A useful tool in many safeguards approaches is the on-line monitoring of enrichment in process pipes. One aspect of th...